code: def update(self, labels, preds):
      # label = labels[0].asnumpy()
      pred = preds[-1].asnumpy()
      # print('in loss', pred.shape)
      # print(pred)
      loss = pred[0]
      self.sum_metric += loss
      self.num_inst += 1.0
  
file_path: insightface/recognition/arcface_mxnet/metric.py
imports: import numpy
  import mxnet
label_desc: Use image node_id 2 for calling the LossValueMetric obj's underlying member method code with example usage: obj.update(labels, preds) without return types